好的,你有正交矩阵和四边形,那么问题是什么,将四边形的模型视图矩阵转换到所需位置(x,y,z = 0),将其乘以正交矩阵,将相乘的矩阵传递给顶点着色器,乘以顶点位置通过你的矩阵并完成:),我没有在代码中使用任何lookat函数来执行此操作,但我有自己的矩阵计算代码,其部分代码来自一些bada教程,对于投影矩阵,我有其他函数。
void
Letter::Ortho(Matrix* result, float fovy, float aspect, float nearZ, float farZ)
{
GLfloat frustumW, frustumH;
frustumH = tanf(fovy / 360.0f * PI) * nearZ;
frustumW = frustumH * aspect;
Frustum(result, -frustumW, frustumW, -frustumH, frustumH, nearZ, farZ);
}
void
Letter::LoadIdentity(Matrix* result)
{
memset(result, 0x0, sizeof(Matrix));
result->m[0][0] = 1.0f;
result->m[1][1] = 1.0f;
result->m[2][2] = 1.0f;
result->m[3][3] = 1.0f;
}
void
Letter::Frustum(Matrix *result, float left, float right, float bottom, float top, float nearZ, float farZ)
{
float deltaX = right - left;
float deltaY = top - bottom;
float deltaZ = farZ - nearZ;
Matrix frustum;
if ((nearZ <= 0.0f) || (farZ <= 0.0f) ||
(deltaX <= 0.0f) || (deltaY <= 0.0f) || (deltaZ <= 0.0f))
{
return;
}
frustum.m[0][0] = 2.0f * nearZ / deltaX;
frustum.m[0][1] = frustum.m[0][2] = frustum.m[0][3] = 0.0f;
frustum.m[1][1] = 2.0f * nearZ / deltaY;
frustum.m[1][0] = frustum.m[1][2] = frustum.m[1][3] = 0.0f;
frustum.m[2][0] = (right + left) / deltaX;
frustum.m[2][1] = (top + bottom) / deltaY;
frustum.m[2][2] = -(nearZ + farZ) / deltaZ;
frustum.m[2][3] = -1.0f;
frustum.m[3][2] = -2.0f * nearZ * farZ / deltaZ;
frustum.m[3][0] = frustum.m[3][1] = frustum.m[3][3] = 0.0f;
Multiply(result, &frustum, result);
}
所以,用这段代码:
LoadIdentity(&matPerspective);
Ortho(&matPerspective, 60.0f, TEXMANAGER.aspect, -1.0f, 20.0f);
LoadIdentity(&matModelview);
Translate(&matModelview, x ,y ,z);
Scale(&matModelview,size);
//Rotate(&matModelview, 0.0f, 1.0f, 0.0f, 1.0f);
Multiply(&posMatrix, &matModelview, &matPerspective);
并将 posMatrix 传递给着色器:)